Your retirement accounts, those shares of stock your great uncle left you and the cash you have set aside to dabble in the market — broadly speaking, this disparate collection of accounts is your portfolio.

Portfolio management — done on your own or by a professional portfolio manager or an automated investing service — means coming up with and executing a cohesive investing strategy based on your goals, timeline and stomach for risk.

Portfolio management decisions are guided by three main factors: an investor's goals, timeline and risk tolerance.

1. First, decide your goals, be they retirement, a home renovation or a child's education. Then determine how much money you need to save.

2. Next, decide when you need the money you are investing, and if that date is set in stone or flexible. Your timeline helps inform how aggressive or conservative your investing strategy needs to be. Most investment goals can be mapped to short-, intermediate- and long-term time horizons, loosely defined as three years, three to 10 years and 10 or more years. If, for example, you need the money within three years, you will want to minimize your exposure to the short-term volatility of the stock market.

3. Decide how much risk you can accept, because that is another key driver behind diversification decisions, or the mix of assets you hold in your portfolio. The more risk you are willing to take, the higher the potential payoff. But high-risk investments also take time to mature. The goal is to strike the right risk-reward balance, picking investments that will help you achieve your goals but not keep you up at night with worry.

Portfolio management isn't solely about building and managing an investment portfolio, though. Here are some other things to consider.

For example, for retirement, do you want a taxable account like a Roth IRA or a tax-advantaged one like an IRA or 401(k)?

Plus, how do you want to handle rebalancing, the act of buying and selling investments within the portfolio? Portfolio managers do this to maintain the target allocation originally set for the investment strategy.

Part of this is how much you or your investment manager want to be involved in day-to-day decisions. Active portfolio managers take a fee to watch investments and make individualized changes. Passive management involves choosing funds and letting the fund manager make the decisions.

These services also charge a percentage of assets managed, but because there is little need for active hands-on investment management, that cost is a fraction of fees for actively managed accounts.

Yochim writes for NerdWallet.